In general, a light source apparatus used for an optical apparatus, such as a liquid crystal projector or a DLP projector, is integrally made up of a high intensity discharge lamp, such as a high-pressure mercury discharge lamp, which is a light source, a reflection mirror which condenses light emitted from the high intensity discharge lamp, and reflects it towards a front opening, and an auxiliary start-up light source which decreases starting voltage of the high intensity discharge lamp, and improves the starting nature of the high intensity discharge lamp.
FIG. 6 is an explanatory diagram showing the structure of a light source apparatus according to the prior art. The light source apparatus comprises an extra-high pressure mercury lamp 1 (hereinafter referred to as a discharge lamp), a reflection mirror 2 which surrounds a discharge lamp 1, a base 3 which is fixed to a neck portion 21 of the ellipse reflection mirror 2, a conductive holding member 7 which is fixed to the reflection mirror 2 by a fixed member, an auxiliary start-up light source 4 which is held by the conductive holding member 7 so as to be arranged in the reflection mirror 2.
One of sealing portions of the discharge lamp 1 is inserted in a through hole formed in the neck portion 21 of the reflection mirror 2 so as to be fixed to the base 3 by the adhesive agent. A lamp power feeder 11a is connected to an external lead 11 which extends from one sealing portion of the discharge lamp 1, and the other end of the lamp power feeder 11a is connected to an electric supply terminal 5 which is fixed to the base 3. A lamp power feeder 12a is connected to an external lead 12 which extends from a sealing portion of the other side of the discharge lamp 1. The other end of the lamp power feeder 12a is led out from an opening 22 of the reflection mirror 2 to the outside of the reflection mirror 2, so as to be connected to an electric supply terminal 8 which is fixed to the reflection mirror 2.
FIGS. 7A and 7B are diagrams for explaining the connection structure of the auxiliary start-up source and the reflection mirror. The conductive holding member 7 and the electric supply terminal 8 are attached to the opening 22 of the reflection mirror 2 by the fixed member. That is, the fixed member is made up of a cylindrical grommet member 90 and an inner tooth washer 91. After the cylindrical grommet member 90 is inserted in an opening of the conductive holding member 7, the opening 22 of the reflection mirror 2, an opening of the electric supply terminal 8, and the inner tooth washer 91, these members are integrally fixed by bending the tip of grommet member 90 so that a projected tip may be opened and then processing it. Moreover, the lamp power feeder 12a is inserted in an inner through hole of the grommet member 90, and crimped (or squeezed) with the high-pressure power feeder connected with a power supply at a cylindrical section of the electric supply terminal 8.
Where, in the auxiliary start-up source 4, a pair of external electrodes is provided so as to be apart from each other on the outer surface of the both ends of the electric discharge container. An end portion, which is in a side where one of the external electrodes of the electric discharge container is provided, is inserted in the cylindrical section provided in the conductive holding member 7. The conductive holding member 7 not only holds the auxiliary start-up light source 4 but also functions as an electric path to the one of external electrodes of the auxiliary start-up light source 4. The external electrode of the other side of the auxiliary start-up light source is electrically in a float state. Refer to Japanese Laid Open Patent No. 2007-66742.